If you're reading me and not Christopher, check this out. He's teaching an online course for free, during the two-week span from March 17 to 30. If you're a middle school teacher and have the hour a day to commit to it, I bet it will be loads of fun.

Friday, December 7, 2012

... which is so big it feels infinite sometimes. I've been following hundreds of math-related blogs for the past few years. How delightful to discover a whole niche of math-related goodies I'd never dreamed of.

Have you heard of 3-D printers? They're a basic part of the plot of Makers, by Cory Doctorow, a sci-fi novel I read a few weeks ago. (I bought the UK edition at my local independent bookstore in California. You can download the book for free at Cory's website.) Those 3-D printers are already real. (I think I knew that, but I haven't seen one in action yet.)

Christian Perfect, over at Aperiodical, has just posted a roundup of cool mathy stuff being made on 3-D printers. You can get designs at Thingiverse if you have access to a 3-D printer (which cost between $700 and thousands of dollars), and you can buy stuff at Shapeways. Christian reported the prices in pounds, so I had to visit the site to see if things were affordable in dollars. Yep. If you'd like to give math-inspired earrings as a gift, you can do it. Or weird dice. Or beautiful little sculptures. (My math-loving niece is getting this one.)

I have to wonder whether Cory had Shapeways in mind as he wrote Makers. This line from Shapeways' webpage sounds like something right out of the book:

"Shapeways is a spin-out of the lifestyle incubator of Royal Philips Electronics. Investors include Lux Capital and Union Square Ventures in New York and Index Ventures in London."

The San Francisco Chronicle has an article on 3-D printers that might help you get oriented. I just spent an hour or so looking for articles and watching youtube videos. I didn't find much that's well-written or exciting to watch, but I have a better basic understanding now of what they are.

After I was almost done ordering those earrings, I saw that they'd ship after the holidays. Apparently some things will ship faster. It depends on the materials. Also, if you do buy earrings, make sure you're getting two; some are priced per earring.

Tuesday, December 4, 2012

The first puzzle shouldn't be too hard. The second ... is tough. It's by Mike Shenk, who has a site called puzzability, and is interviewed here.

I wish you all peace and joy during these winter holidays.

Holiday Logicby Sue VanHattum

1. The Green girl’s favorite Christmas tradition is singing carols.
2. The Brown boy celebrates Kwanzaa indoors.
3. DJ and Jordon joined their friend in her candle lighting ceremony.
4. Layla and Amani joined their friend for his annual walk through the woods.
5. The Gold girl came to Jordon’s house to join his family in their feast.
6. The Fox family celebrate the Yuletide, and Amani comes to their party.
7. Amani couldn’t make it to the Gold family’s Hanukkah celebration.

Each
child celebrates just one holiday with one special activity as a
tradition in their family, though they do join in the fun with their
friends this year. Your mission: Decide who celebrates each holiday, and
what they do to celebrate.

Oh Deer! A logic problem by Mike Shenk(first published in Games Magazine, December 1992)

Twas the night before Christmas, and at the North Pole
The last-minute planning was taking its toll.
As Santa was hastily making a scheme
For the placement of deer in his sleigh-pulling team,
The good Mrs. Claus was crocheting bright bows
To be worn by these reindeer (four bucks and four does).

The ribbons were colored in eight festive hues:
One ocher, one rose, one cerise, one chartreuse,
One maroon, one magenta, one white, and one blue.
(These ribbons helped Santa keep track of who's who.)
The deer pulled the toy-laden sleigh in four rows,
Arranged so no row held two bucks or does.

The order of pullers was changed year by year,
For Santa was thoroughly fair with his deer.
He summoned the elves and instructed them thus:
"Let's hitch up the reindeer with minimum fuss.
The bow on the buck behind Dasher is white,
While Blitzen, a doe, sees cerise to her right.

The blue bow is nearer my sleigh than is Dancer,
But nearer the front of my team than is Prancer.
The doe in chartreuse gets a front-of-team honor,
But not on the same side as Cupid or Donner.
Now Comet stands two spots ahead of the rose.
And three deer of four on the right side are does.

The cerise bow is worn two in back of maroon,
One of which is beside the bright ocher festoon.
Oh-Cupid's in front of a buck, by the way.
Well, that's how they line up for pulling my sleigh.
I trust that you elves, being clever, now know
Each reindeer's position and color of bow."

In no time each colorful ribbon was tied
And the team was hitched up for the transglobal ride.
Can you ascertain where each member fits in?
Who's Comet? Who's Cupid" Where's Donner? And Blitzen?
Who's Dasher? Who's Dancer" Where's Vixen? And Prancer?
With logical thought, you'll determine the answer
And write down the color and place for each deer.
Happy Christmas to all, and to all much good cheer!

I also wanted to mention the cool math teacher in the book. I like how he offers his best students some personal challenges.

Mr. Muraki was our math teacher. He had taken a liking to us,
and would regularly slip us index cards with all sorts of interesting
math problems. They rarely had anything to do with our classwork,
which made for a refreshing change of pace. We always looked forward
to what he would come up with next.

I like this. I think I'll try to do it next semester.

I'll write a more complete review once I've managed to read the whole thing.